Remote power down control of a device

ABSTRACT

In remote power down control of a device configured for externally initiated remote power down, such as over a network, all externally connected sources of valid power down requests for the device is monitored; and the device is powered down in response to a combination of either of a received power down request and a time out with respect to each of the sources of valid power down requests for the device.

CROSS REFERENCE TO RELATED APPLICATIONS

This Application is a Continuation of U.S. patent application Ser. No.15/427,621, filed on Feb. 8, 2017, which is a Continuation of U.S.patent application Ser. No. 15/161,595, filed on May 23, 2016, now U.S.Pat. No. 9,632,799, which is a Continuation of U.S. patent applicationSer. No. 14/812,174, filed on Jul. 29, 2015, now U.S. Pat. No.9,383,810, which is a Continuation of U.S. patent application Ser. No.14/470,040, filed on Aug. 27, 2014, now U.S. Pat. No. 9,146,612, whichis a Continuation of U.S. patent application Ser. No. 12/573,039, filedon Oct. 2, 2009, now U.S. Pat. No. 8,856,563, each of which are herebyincorporated herein by reference.

FIELD OF THE INVENTION

This invention relates to devices that are situated remotely from hosts,and more particularly, where the power state of the device may becontrolled remotely by the hosts.

BACKGROUND OF THE INVENTION

It is useful to be able to power up and power down devices based uponneed, rather than have them powered all of the time. It is known toexternally power off a remote device that is functional andcommunicating, by sending a command that tells it to power off. In asituation involving multiple hosts, such as a network, a challenge comesin powering off devices that are being used by the multiple hosts.

SUMMARY OF THE INVENTION

Methods, servers, devices, networks, and power controls are provided forremote power down control of a device.

In one embodiment, a method for powering down a device configured forexternally initiated remote power down, comprises the steps of:

monitoring of all externally connected sources of valid power downrequests for the device; and powering down the device in response to acombination of one of a received power down request and a time out withrespect to each of the sources of valid power down requests for thedevice.

In a further embodiment, a received power down request of a source isinvalidated by subsequent activity for the device received from thesource.

In a still further embodiment, the activity comprises at least one of apower up request and a command with respect to the device.

In another embodiment, the sources of valid power down requests comprisesources logged in with respect to the device.

In a further embodiment, a power down request comprises at least one ofa specific power down request and a log off request from the source.

For a fuller understanding of the present invention, reference should bemade to the following detailed description taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic illustration of hosts and of a device which mayimplement the present invention;

FIG. 2 is a block diagram of an exemplary device of FIG. 1 with anoptical serial interface;

FIG. 3 is a diagrammatic illustration depicting a table maintained bythe device of FIG. 1;

FIG. 4 is a flow chart depicting an exemplary method of operating thedevice of FIG. 1;

FIG. 5 is diagrammatic illustration of a network and server which mayimplement the present invention;

FIG. 6 is a block diagram of the server and computer processing systemof FIG. 5;

FIG. 7 is a diagrammatic illustration depicting a table maintained bythe server of FIG. 5; and

FIG. 8 is a flow chart depicting an exemplary method of operating thesystem of FIG. 5.

DETAILED DESCRIPTION OF THE INVENTION

This invention is described in preferred embodiments in the followingdescription with reference to the Figures, in which like numbersrepresent the same or similar elements. While this invention isdescribed in terms of the best mode for achieving this invention'sobjectives, it will be appreciated by those skilled in the art thatvariations may be accomplished in view of these teachings withoutdeviating from the spirit or scope of the invention.

Referring to FIG. 1, an example of a system 100 is illustrated in whichhosts 105, 106 provide commands to device 200. An example may comprise adata storage device and the hosts provide commands and data to device200 for storage and retrieval of the data. The hosts 105 may beconnected to the device 200 by means of a network 107, such as throughNetwork Attached Storage (NAS), or a plurality of hosts may comprisepartitions or otherwise form a host system 106 that may be directlyconnected to the device 200. The device 200 may comprise a single entityor may comprise a system subject to being powered down by the hosts.

Many means of implementing communications comprising the directconnection or network communication of FIG. 1 are known to those ofskill in the art.

FIG. 2 illustrates one example of a communication implementationcomprising optical communications to an optically coupled device 200.Device 200 comprises an operational element 202, storage element 204,optical communication port 206, and power supply 250. Operationalelement 202, storage element 204, and port 206 communicate internallyvia internal interface 208. Power supply 250 receives power from anexternal source via cable 252, and converts it to one or more DCvoltages 254 to power the various elements of device 200. Operationalelement 202 comprises any suitable processing device and may compriseassociated memory, flash, input/output ports, and support logic, as wellas application specific elements. Storage element 204 comprises one ormore data storage media, any of which may comprise disk drives,removable data storage, solid state storage devices, sequential storagedevices, holographic and other optical devices.

Device 200 communicates with other devices through port 206. Port 206 isconnected to an optical cable 114 of one of the connections of FIG. 1 tohosts 105, 106 via connector 238 and comprises optical fibers 234 and236. Port 206 comprises a high level protocol command processor 207, lowlevel reception and transmission protocol converters 210 and 220, andoptical transducer elements 230 and 226 as known to those of skill inthe art. Parallel connections 212 and 222 link command processor 207with converters 210 and 220 respectively, and may, for example, be one32-bit word wide, and comprise at least one control signal, allowing thedifferentiation between data words and control words.

High level command processor 207 sends words to be transmitted viaconnection 222 to low level transmission protocol converter 220, whichencodes them from their native 32-bit hexadecimal value to an encoded40-bit value, using an 8-bit/10-bit encoding scheme known in the art.The encoding scheme is designed to provide a minimal number oftransitions between high and low states, and to maintain DC balance whenencoded data is sent over serial interfaces. Serial encoded words arethen transmitted via differential electrical signals 232 to opticaltransmitter element 230, which converts the electrical signals tooptical signals and transmits the optical signal into fiber 234.

Optical signals from fiber 236 are received by optical receiver element226 and converted to differential electrical signals 228 to low levelreception converter 210, which receives the serial information, detectsthe delimiters and converts the serial information into 40-bit words,detects the data and control words, and decodes the 40-bit words totheir native 32-bit hexadecimal values. The decoded words are thenreceived by high level command processor 207 via parallel connection212, along with indications of control words via control signals.

It is useful to be able to power up and power down devices based uponneed, rather than have them powered all of the time. It is known toremotely power off a device that is functional and communicating, bysending a command that tells it to power down. A powered down state maycomprise any situation of reduced power or power off to elements of thedevice, and a powered on state may comprise any situation of fully orpartially operational powered on elements of the device. “Remote” meansthat the device being powered up or powered down is connected to thehost via a communication link. The “remote” device may or may not be inthe immediate vicinity of the host.

A challenge comes in powering off devices 200 that are being used bymultiple hosts 105, for example, on the network. Typically, a user willoperate a host to power down an unused device to save energy, butanother host on the network will still be using the device and willinstead want the device to be powered up. The delay introduced bypowering up a powered down device may prove undesirable by the secondhost.

Referring to FIGS. 1, 2, 3 and 4, in one embodiment, the device 200 isconfigured for an externally initiated remote power down by any of hosts105 or of host 106. In one embodiment, a method is provided for poweringdown the device 200, comprising monitoring the activity of all theexternally connected sources 105, 106 of valid power down requests forthe device 200; and powering down the device in response to acombination of either a received power down request or an inactivitytime out with respect to each of the sources 105, 106 of valid powerdown requests for the device. In one example, the device is coupled tothe hosts 105, 106 via at least one optical communication link, such asFibre Channel. In an existing Fibre Channel SCSI protocol, each host mayserve as an initiator, and an initiator is considered a “source” only ifthe initiator is currently logged in (in Fibre Channel terminology,short for completed port login and process login), for example, at port206 and high level protocol command processor 207, in step 258 of FIG.4. Initiators, for example, get to the login-complete state by issuing aport login extended link service that is accepted by the target, andalso a process login extended link service that gets accepted by thetarget as well.

In one embodiment, the method is controlled by the operational element202 of the device, and may utilize the storage element 204, if any, andselectively operate the power supply 250 via link 256.

The process login acceptance may be conducted by the operational element202, and, in step 259, the accepted initiator is added to the list ofsources, for example, in table 260 of FIG. 3, where the sources(initiators) are identified by their node port names 261, world widenode names 262, and world wide port names 263. Table 260 representsinformation stored, for example, by the operational element 202 whichmay or may not be in the form of an actual table.

In step 270, the logged in sources 105, 106 are monitored for activity,and monitored for power down or log off commands 271. In one example,activity comprises the sending or receiving of Fibre Channel frames, butFibre Channel primitives do not count as activity. In another example,the activity comprises either a command or a power up request withrespect to the device. The power up request may be considered activitybecause a power down request from the same initiator that may havepreceded it may not have resulted in an actual power down.

In step 273, if there is no activity, the monitoring continues for thesource in step 270. If there is activity, step 275 detects whether theinput is a power down request or a log off command, and, if so, in step280, the source is marked in column 282 of table 260. The power downrequest and log off command are considered to both indicate that thehost is releasing the device.

If step 280 indicates that the input is not a power down request or logoff command, step 285 determines whether column 282 had previously beenmarked to identify a power down request from the source. The activityidentified in step 273 invalidates any previous power down request inthat the source apparently considers the device to be powered up andactive, and the previous power down request in column 282 is reset instep 287.

In step 290, the activity identified in step 273 updates the activitymonitoring for the source.

Inactivity with respect to the source is measured in step 292continuously, periodically, or randomly, and the measurement is takenindividually or as a part of the status discovery process of step 293,as will be discussed. Inactivity measurement may comprise any of variousmeasurements, such as a less than minimum amount of activity measuredover a given time period, or as a lack of any activity in a given timeperiod, for example, as measured by a timer. In one embodiment,inactivity comprises the timing out of a timer that had been reset atthe last activity by the source. In one example, the time periodcomprises a 10 minute period. In another embodiment, inactivitycomprises only one instance of activity in a 15 minute period togetherwith a 10 minute time period without any activity.

If, in step 295, the inactivity threshold is not met, the processreturns to step 270 to continue monitoring.

If the inactivity threshold of step 295 is met, step 296 marks thesource in column 297 of table 260.

Step 293 discovers the power down and inactivity status of all thelogged in sources. Step 293 may be conducted continuously, periodically,or randomly, and may initiate the individual inactivity measurement ofeach of the sources of step 293.

Step 298 is illustrated in column 299 of table 260 and comprises the“OR” function of the power down request (or log off) of column 282 andthe inactivity measurement of column 297. Column 299 is for the purposeof illustration only and need not be specifically identified. If all ofthe logged in sources have either or both the power down request (or logoff) of column 282 and the inactivity measurement of column 297 marked,step 300 powers off the power supply 250 of device 200. Otherwise, themonitoring activity continues in step 270.

Thus, where multiple hosts are logged in and are sources of power downrequests for device 200, the power down control, for example, of theoperational element 202, provides the actual power down of the device,so that a user that operates a host to power down an unused device, willnot adversely affect another host that is still using the device. Thesecond host will not have to power up a powered down device.

FIG. 5 illustrates a server 302 configured to power down target devices310, 312, 314, 316, and/or 318 arranged in a network 301 in accordancewith an embodiment of the invention. In one example, initiator ports350, 354 are configured to provide communication over the network tomultiple devices or initiators 304, 306, and/or 308 that are potentialsources of a power down for the devices. Device ports 305 are configuredto provide communication over the network to the devices to be powereddown. The server comprises at least one data handling system 340.Alternatively, the server may comprise a processor within a switch,which controls the network 301.

FIG. 6 illustrates an example of a data handling system 340 which mayimplement the present invention and may implement the function of theserver 302. Alternatively, the data handling system 340 may also controlthe switching function. Still alternatively, the switch function may becarried out by one entity and the server function is conductedseparately. Referring to FIG. 6, the data handling system 340 comprisesa computer processor system 345 configured to operate the server, thecomputer processor system having computer processor(s) 347, andmemory(ies) 348 configured to store information and computer readableprogram information for operating the computer processor(s). Herein,referring to both data handling system 340 and the processor foroperational element 202 of the device 200 of FIGS. 1 and 2, “computerprocessor”, “computer processing system” or “control” may comprise anysuitable logic, programmable logic, microprocessor, and associated orinternal memory for responding to program instructions, and theassociated or internal memory may comprise fixed or rewritable memory ordata storage devices. The program information may be supplied to thesubsystem control or memory from a host or via a data storage drive ordisk array, or by an input from a floppy or optical disk, or by beingread from a cartridge, or by a web user interface or other networkconnection, or by any other suitable means. The program information thusmay comprise one or more program products comprising a computer useablestorage medium having computer usable program code stored therein foroperating the data handling system 340, or similar types of systems ordevices.

Initiator ports 350, 354 may comprise one or more host adapters, FibreChannel ports, one or more FICON ports, one or more ESCON ports, one ormore SCSI ports, or other suitable ports. Each host interface isconfigured to communicate with a host system of network 301 of FIG. 5such that the server can handle I/O from any host or using entity. Inone example, the initiator ports 350, 354 connect to an Ethernet basednetwork 301 via standard TCP/IP protocols.

Device ports 305 may comprise device adapters, for example for serialinterconnections, such as RS-232 or RS-422, Ethernet connections, SCSIinterconnections, ESCON interconnections, FICON interconnections, orconnections to a Local Area Network (LAN), a private Wide Area Network(WAN), a public wide area network, Storage Area Network (SAN),Transmission Control Protocol/Internet Protocol (TCP/IP), the Internet,and combinations thereof.

An example of a data handling system 340 or server 302 comprises an IBM®Enterprise Storage Server, IBM® Model DS 8000, or other comparablesystem.

Referring to FIGS. 5 and 7, FIG. 7 depicts a remote power managementtable 360 maintained by the server 302 of FIG. 5 to manage the powerstate of each of respective target devices. The table 360 representsinformation stored, for example, by the data handling system 340 whichmay or may not be in the form of an actual table. Column 361 is the portname of a respective target device 310, 312, 314, 316, and/or 318.Column 362 contains the address of the respective device, and column 363gives the type of connection for the device. Column 364 indicateswhether the respective device is configured to power down in response toa power down command by the server 302, making it capable of “remotepower management” (RPM), and column 365 indicates whether thatcapability is enabled. Column 366 indicates the type of device. Column367 indicates the RPM status, either currently powered on or poweredoff, and column 368 contains a time stamp (TS) of the last time thedevice was powered on, if it is currently powered off. If the device iscurrently powered on, this field is zero. Column 369 contains a list ofthe addresses of all initiators that are currently accessing the device,and are “sources”. The initiators of column 369 are also only thosesources that are currently active, and not inactive.

Referring to FIGS. 5, 7 and 8, an embodiment of the remote powermanagement begins at step 402, and, in step 404, performs devicediscovery to identify the initiator and target devices for table 360. Instep 406, a pointer (PTR) is set to the first device in the list ofdevices from the discovery process. For that device, step 408 checks forthe current device in the table 360. If the device is not found, step410 adds a row to the table 360 for the new device. For the new devicefound in step 408 or the device already listed in the table 360 asdetermined by step 408, step 412 sends an inquiry command, such as aFCP-SCSI (Fibre channel protocol) Inquiry, to determine the devicecharacteristics in order to populate the rest of the new table entry.Step 414 fills out or updates the rest of the table entry with thedevice data returned from the inquiry command. In one embodiment, step414 also clears column 369, the active “source” initiators for thedevice, to all blanks. Step 414 also clears and sets to all “0” thecolumn 368, last powered on time stamp, for the device. Step 416increments the pointer and then in step 418 checks whether all devicesof the network have been processed. If all devices have not beenprocessed, the process returns to step 408.

If step 408 indicates that all discovered devices have been processedand their entries created or updated, step 424 sets the pointer to thefirst device row in the table 360. If the device had not been found indiscovery of step 426, steps 427 and 428 ascertain its status. Step 427checks the last powered on time stamp in column 368 of table 360. If thetime stamp of step 427 is zero, the device was powered up during aprevious discovery process, so in step 430, the last powered on timestamp in column 368 is set to the current time. If in step 427, it wasdetermined that the last powered on time stamp was not zero, the processcontinues at step 428, where it checks, for example, for a timeout,indicating that the device has become inactive. As discussed above, atimeout is one means of indicating that a device has become inactive,and another means is to determine whether the activity in a time periodhas fallen below a threshold.

If the timeout has occurred, step 429 removes the device entry from thetable 360 as will be discussed. If the device was an initiator, step 429also clears the active initiator address of the device from column 369for any device for which it had been a source. Thus, column 369 for atarget device that may be remotely powered down indicates only thoseinitiators that are a source and are not timed out.

A “No” result from step 428, or a completion of step 429, or acompletion of step 430, or step 426 indicating that the current devicewas found during the discovery process, leads to step 431 whichincrements the pointer to the next device row in the table 360. Step 432determines whether all of the devices in the table 360 have beenprocessed. If not, the process returns to step 426 to process the nextentry.

If all the devices have been processed, step 434 checks for an activeRPM request, which may comprise a power down request or a power uprequest. If no RPM request is detected, step 468 detects whether a statechange notification (SCN) has been received regarding any of the activedevices. A state change notification, such as a log off command,requires that the table 360 be updated, so the process returns to step404 to perform discovery. If there is no state change notification, step434 is repeated.

If step 434 indicates that the server 302 has received a commandrequesting the RPM state of a device be set, such as a power downrequest, the process flows to step 436 to check whether the device is inthe table 360. If not, an error is returned in step 442 with a sense keyindicating that the device was not found, and the process returns tostep 468.

If the device is found in the table, step 438 checks the table todetermine whether the respective device is RPM capable (column 364) andwhether the RPM is enabled (column 365). If step 444 indicates that theRPM request is a power down request, step 454 uses column 369 of thetable 360 to determine whether any other initiator is active and usingthe respective device, a “source” that has not timed out. If step 454indicates no other initiators are active sources for the device, step458 sends the requested power down command to the target device via port305.

If other initiators are active and using the device, a “source” for thedevice, step 456 determines whether all the other sources are timed outand are inactive with respect to the device, or have issued a power downrequest for the device. In one embodiment, step 456 checks whether thedevices listed in column 369 are still found in the directory of theserver or of the switch (called a directory name server). If theinitiators were powered off or malfunctioned and are no longeroperating, they will time out with the directory name server, and willbe removed from the name server list. If all of the initiators found inthe table, other than the initiator requesting that the device bepowered down, are no longer in the directory name server, step 458 sendsthe requested power down command to the target device via port 305. Ifin step 256, any of the other initiators in column 369 for the deviceare still found in the name server, step 449 updates the initiatorstatus, removing the initiator requesting the device be powered downfrom column 369 for the device. Any initiators that were not found inthe directory name server that are listed in column 369 for the deviceare also removed.

Thus, the removal of the initiators accomplishes the function ofindicating either that they have become inactive or that they haverequested a power down of the device, fulfilling the “OR” function forthose initiators. As the result, the absence of other sources fromcolumn 369 indicates that the “OR” function of the power down request(or log off) and the inactivity measurement are complete for thoseinitiators for the device, and, if completed, step 454 would have been a“No” and step 458 would have sent the requested power down request.

If step 456 determines that at least one other source remains active andhas not issued a power down request for the device, for example, byremaining in column 369 for the device, the device is not powered down.Step 449 is completed as discussed above, and the process returns goodstatus with respect to the power down request in step 464.

If step 458 sent the requested power down command, step 460 checks thestatus returned by the device. If the command to the device wassuccessful (the device indicating good status indicating it is poweringdown), the process updates the device status in column 367 of table 360.Also in step 462, if the requested command was a power down command, theprocess saves the current time stamp in column 368 for the device andremoves all initiator addresses (if there are any remaining) from column369. If the command requested was a power up command, to be describedsubsequently, the process adds the initiator address to column 369, andsets the time stamp in column 368 to zero. The process returns goodstatus to the initiator in step 464, and moves to step 468. If step 460was not successful, the process returns a check condition to theinitiator in step 466 with status indicating that the command failed,and then moves to step 468.

If in step 444, it is determined that the initiator is requesting thatthe device be powered up, the process continues at step 446 to checkwhether the initiator is listed in column 369 for the device. If it isnot, step 452 adds the initiator's address to the list of initiatorsthat are using the device in column 369. If in step 446, the initiatoris already listed, or upon completion of step 452, the process flows tostep 458 and the power up command is sent to the device.

Thus, the server 302 monitors, via the initiator ports 350, 354,activity of network connected sources 304, 306, 308 of valid power downrequests for each of several devices 310, 312, 314, 316, 318; andprovides a power down command to a device, via device ports 305, inresponse to a combination of either received power down request or aninactivity time out with respect to each of the sources of valid powerdown requests for that device.

Referring to FIGS. 2 and 6, the implementations may involve software,firmware, micro-code, hardware and/or any combination thereof. Theimplementation may take the form of code or logic implemented in amedium, such as memory 348, storage element 204, and/or circuitry 202 or347 where the medium may comprise hardware logic (e.g. an integratedcircuit chip, Programmable Gate Array [PGA], Application SpecificIntegrated Circuit [ASIC], or other circuit, logic or device), or acomputer readable storage medium, such as a magnetic storage medium(e.g. an electronic, magnetic, optical, electromagnetic, infrared, orsemiconductor system, semiconductor or solid state memory, magnetictape, a removable computer diskette, and random access memory [RAM], aread-only memory [ROM], a solid state disk drive [SSD], a rigid magneticdisk and an optical disk, compact disk-read only memory [CD-ROM],compact disk-read/write [CD-R/W], DVD, and BD).

Those of skill in the art will understand that changes may be made withrespect to the methods discussed above, including changes to theordering of the steps. Further, those of skill in the art willunderstand that differing specific component arrangements may beemployed than those illustrated herein.

While the preferred embodiments of the present invention have beenillustrated in detail, it should be apparent that modifications andadaptations to those embodiments may occur to one skilled in the artwithout departing from the scope of the present invention as set forthin the following claims.

What is claimed is:
 1. A method for powering down a device configuredfor externally initiated remote power down, each of a plurality ofexternally connected sources of valid power down requests being loggedin for said device, the method comprising the steps of: powering downsaid device in response to one of each of said plurality of externallyconnected sources and an inactivity time out with respect to one of saidplurality of externally connected sources occurring.
 2. The method ofclaim 1, wherein a received power down request of one of said pluralityof externally connected sources is invalidated by subsequent activityfor said device received from said one of said sources.
 3. The method ofclaim 2, wherein said activity comprises at least one of a power uprequest and a command with respect to said device.
 4. The method ofclaim 3, wherein said power down request comprises at least one of aspecific power down request and a log off request from said one of saidsources.
 5. A server configured to power down at least one devicearranged in a network, each of a plurality of externally connectedsources of valid power down requests being logged in for said at leastone device, said server comprising: at least one device port configuredto provide communication over said network to said at least one device;at least one initiator port configured to provide communication oversaid network to at least one network; and at least one data handlingsystem configured to: power down said at least one device in response toone of each of said monitored of said plurality of externally connectedsources and an inactivity time out with respect to one of said pluralityof externally connected sources occurring.
 6. The server of claim 5,wherein said data handling system is configured to invalidate a receivedpower down request of one of said plurality of externally connectedsources in response to subsequent activity for said respective devicefrom said one of said sources.
 7. The server of claim 6, wherein saidactivity comprises at least one of a power up request and a command withrespect to said respective device.
 8. The server of claim 7, whereinsaid power down requests comprise at least one of a specific power downrequest and a log off request from said one of said sources.
 9. A deviceconfigured to perform at least one function and configured to powerdown, each of a plurality of externally connected sources of valid powerdown requests being logged in for said device, said device comprising:at least one port configured to provide communication over a network; atleast one function apparatus to perform said at least one function inresponse to commands received via said at least one port; and at leastone control system configured to: power down said device in response toone of each of said plurality of externally connected sources and aninactivity time out with respect to one of said plurality of externallyconnected sources occurring.
 10. The device of claim 9, wherein saidcontrol system is configured to invalidate a received power down requestof a source in response to subsequent activity for said device from saidat least one of said plurality of externally connected sources.
 11. Thedevice of claim 10, wherein said activity comprises at least one of apower up request and a command with respect to said device.
 12. Thedevice of claim 11, wherein said sources of valid power down requestscomprise sources logged in, via said at least one port, with respect tosaid device.
 13. The device of claim 11, wherein said power down requestcomprises at least one of a specific power down request and a log offrequest from said source.
 14. A network, connecting each of a pluralityof externally connected sources of valid power down requests for beinglogged in, the network comprising: a communication network; and at leastone device connected to said communication network, said at least onedevice configured to: power down said device in response to one of eachof said plurality of externally connected sources and an inactivity timeout with respect to one of said plurality of externally connectedsources occurring.
 15. The network of claim 14, wherein said at leastone device is configured to invalidate a received power down request ofone of said plurality of externally connected sources in response tosubsequent activity for said device from said one of said plurality ofsources.
 16. The network of claim 15, wherein said activity comprises atleast one of a power up request and a command with respect to saiddevice.
 17. The network of claim 16, wherein said power down requestcomprises at least one of a specific power down request and a log offrequest from said source.
 18. A power control for a network attacheddevice, using a plurality of logged in externally connected sources ofvalid power down requests for said network attached device, the powercontrol comprising: an input configured to detect commands received bysaid network attached device from said network; and at least one controlsystem configured to: power down said network attached device inresponse to one of each of said plurality of externally connectedsources and an inactivity time out with respect to one of said pluralityof externally connected sources occurring.
 19. The power control ofclaim 18, wherein said at least one control system is configured toinvalidate a received power down request of a source in response tosubsequent activity for said network attached device from at least oneof said plurality of externally connected sources.
 20. The power controlof claim 19, wherein said activity comprises at least one of a power uprequest and a command with respect to said network attached device. 21.The power control of claim 20, wherein said sources of valid power downrequests comprise sources logged in with respect to said networkattached device.
 22. The power control of claim 21, wherein said powerdown request comprises at least one of a specific power down request anda log off request from said at least one of said plurality of externallyconnected sources.